Add thinking effort to the Anthropic provider

[kylecarbs]

• I have read CONTRIBUTING.md.
• I have created a discussion that was approved by a maintainer (for new features).

This changes Fantasy to use the upstream Anthropic Go SDK rather than the Charm fork. There seemed to be no differences in the versions, other than it being slightly behind main (80 commits at the time of writing).

[andreynering]

Hey @kylecarbs,

FYI, the fixes we made on the fork were done on the fantasy branch:

• anthropics/anthropic-sdk-go@main...charmbracelet:anthropic-sdk-go:fantasy

It's a good reminder to revisit that, tho. I made these fixes at the time and never checked if these are still needed in the new version nor I updated the fork.

[kylecarbs]

Thanks for the quick response @andreynering. My bad - shoulda checked the ref.

Would it be alright if I submitted a PR updating that branch on the fork then? Seems much safer than pinning to main here and merging a change.

[andreynering]

@kylecarbs Yes. Let's do that in steps: update the fork first and add reasoning effort in a separate PR.

[andreynering]

FYI, I submitted PRs to upstream at the time, but they simply never reviewed them.

• fix(vertex): do not override custom http client when using vertex anthropics/anthropic-sdk-go#238
• feat(bedrock): add support for bearer token authorization on bedrock anthropics/anthropic-sdk-go#245

[kylecarbs]

PR here: charmbracelet/anthropic-sdk-go#1. Just doing some testing.

[andreynering]

@kylecarbs I pushed the update to main. Can you rebase?

Also, I'd just like to understand your motivation to add reasoning effort.

I'm reading the docs and looks like this + adaptive thinking replaces budget_tokens. Good!

Do you want this on Crush on you're using Fantasy yourself? Also, Anthropic models or another Anthropic-compatible API?

[kylecarbs]

@andreynering updated!

I'm using Fantasy myself - lovely library y'all have made. We're using Anthropic models directly.

[andreynering]

@kylecarbs There is a failing test. Otherwise, it looks good!

[kylecarbs]

@andreynering fixing now!

[kylecarbs]

@andreynering should be good now, also rebased on main.

[andreynering]

@kylecarbs Still failing:

--- FAIL: TestGenerate_InvalidEffortReturnsFantasyError (0.00s)
    anthropic_test.go:520: 
        	Error Trace:	/Users/runner/work/fantasy/fantasy/providers/anthropic/anthropic_test.go:520
        	Error:      	An error is expected but got nil.
        	Test:       	TestGenerate_InvalidEffortReturnsFantasyError

[kylecarbs]

@andreynering should be fixed now, sorry about that!

[andreynering]

Hi @kylecarbs!

I made some changes to this PR, mostly cosmetical.

The most relevant behavior change is that I removed the enum validation because I prefer to let the API handle it.

I also opened two PRs on Catwalk and Crush to make this usable in Crush:

• charmbracelet/catwalk#195
• charmbracelet/crush#2318

Thanks for your contribution! This all should be shipped still today.